ABA Electrical Systems & Wiring 3

Question 1

In an audiometer circuit, the attenuator is typically placed:

Accepted Answer

Between the signal generator and the power amplifier

Answer

Placing the attenuator between the oscillator and amplifier ensures that noise from the amplifier is not attenuated, but signal level control is achieved before amplification.

Question 2

Impedance matching between an audiometer and an earphone transducer is important because:

Accepted Answer

It ensures maximum power transfer and prevents signal reflections

Answer

Maximum power transfer occurs when source and load impedances are matched, ensuring accurate and efficient delivery of the test signal to the transducer.

Question 3

A capacitor in an audiometer circuit is used to block DC while passing AC signals primarily because:

Accepted Answer

Capacitive reactance decreases with increasing frequency allowing AC but blocking DC

Answer

Capacitive reactance (Xc = 1/2πfC) approaches infinity as frequency approaches zero (DC), effectively blocking DC while allowing AC signals to pass.

Question 4

Which circuit element in a hearing aid output stage limits maximum acoustic output to protect residual hearing?

Accepted Answer

An automatic gain control (AGC) or output limiting circuit

Answer

AGC circuits and output limiters are specifically designed to prevent the hearing aid from exceeding prescribed maximum output levels (OSPL90).

Question 5

In an electroacoustic analysis setup, a 2-cm³ coupler has a known acoustic impedance because it:

Accepted Answer

Provides a standardized reproducible cavity for consistent SPL measurements

Answer

The standardized volume of the 2-cm³ coupler provides a reproducible acoustic load, allowing consistent and comparable hearing aid output measurements across facilities.

(ABA) American Board of Audiology Practice Test

(ABA) American Board of Audiology Practice Test

ABA Electrical Systems & Wiring 3